The field of the invention relates generally to optical communication, and more particularly, to systems and methods for optical data transmission over a single fiber or a single free space link.
At least some known radio frequency (RF) photonic designs have been devised that enable high-frequency wideband analog to digital (A/D) conversion using a pulsed laser source as an optical carrier. Under-sampling may be used to affect down-conversion of a band-limited RF signal. Combining these aspects yields an RF photonic microwave to digital converter (MDC). Laser relative intensity noise (RIN) can be reduced by cancellation when a dual-output Mach-Zender modulator (MZM) is used and both outputs are delay matched prior to sampling.
Delay matching the two paths from the MZM to a detector is challenging, especially when the paths are long, such as for a link from a receiving antenna to a remotely located receiver. Equal length transmission lines may not be feasible due to physical obstructions and thermal differences.